This invention relates to rotary combustion engines of trochoidal type, and more particularly to the means of sealing the operating chambers against gas leakage, and of sealing against the leakage of lubricating fluid from the shaft region into the operating chambers.
In the prior art, the customary gas sealing practice for such engines requires a slot extending axially across each rotor apex, a sealing bar disposed in each slot and resiliently urged in the radially outward direction to maintain it in sweeping sealing relation with the inner peripheral surface of the housing, a pin in each side face of the rotor in each apex region receiving the ends of the apex sealing bar, and a plurality of side sealing strips on each side of the rotor with one strip close to and approximately parallel to each working face of the polygonal rotor, with the ends of the side sealing strips either butting against the pins in the apex region or overlapping a shoulder formed on the pin. Oil sealing of the shaft region is achieved by one or more rings in each rotor side face, coaxial with the rotor axis.
Such a system is complex, expensive to manufacture, and difficult to assemble. Some attempts have been made to simplify the problem, as in U.S. Pat. No. 3,853,439 issued Dec. 10, 1974 to Charles Jones, wherein the pins at the rotor apexes have been omitted and a circular gas seal used at the rotor side faces, with the apex sealing bars butting radially against the side seals. However, this arrangement requires that each apex seal be formed of four or even five pieces, with the radial legs of the seal ends extending deeply into the rotor body, and there is the possibility of gas leakage through the spring channel behind the circular seal from one chamber to another. Although such an amount of leakage is acceptable for some uses, in more critical applications it is preferable that such a channel be precluded, as in the present invention.
U.S. Pat. No. 3,251,541 issued May 17, 1966 to Hanns-Dieter Paschke is a similar attempt, but of even greater complexity. The apex seals have radially extending legs at each end butting against a circular side seal, but the radial legs of the apex seals are composed of four pieces each, so that each apex seal assembly consists of nine pieces.
A further atempt is shown in U.S. Pat. No. 3,193,188 issued July 6, 1965 to Max Bentele, wherein in FIG. 13 apex pins nest in notches cut part way through the circular side seals. This not only weakens the side seals, but can cause ineffective sealing operation of the apex seals, which thus are limited in radial travel. Also, good sealing practice requires that the apex sealing bars travel back and forth in the circumferential direction across the width of their slots, in order to permit gas pressure to each the underseal space from the working chamber having the higher pressure at any given portion of the cycle. The lodgement of the apex seal legs in the notches in the side seals links all the apex seal bars together, so that if one seal moves across its slot it must rotate the side seal ring within its groove, and hence move the other apex seals in the same direction, which is contrary to what is desired. Alternatively, frictional forces on the side seals may be sufficient to rotate the rings and move the apex seals when no such movement is desired.
The present invention overcomes these limitations of the prior art.